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5. Environmental Documents

Title:	Upper Mississippi River System-Environmental Management Program Definite Project Report (SL-9) with Integrated Environmental Assessment : Stag Island Habitat Rehabilitation and Enhancement Project (HREP), Pool 25, Mississippi River, Lincoln County, Missouri
Authors:	United States. Army. Corps of Engineers. St. Louis District.
Keywords:	Restoration ecology Environmental protection Environmental management Wetlands Mississippi River
Publisher:	United States. Army. Corps of Engineers. St. Louis District.
Abstract:	The Stag Island Habitat Rehabilitation and Enhancement Project (HREP) is located in Lincoln County, Missouri, near the downstream end of Pool 25, between river miles 247.7 and 249.5. The project area consists of a complex of four islands and surrounding off-channel aquatic habitats located on the inside bend of the river, and totals 486 acres. The four islands are mainly forested and lie low with respect to the river. Aquatic areas include main channel border, side channel, chute, main channel, and island slough habitats. Sedimentation has eliminated or significantly degraded productive off-channel habitats in Pool 25, especially backwaters, which serve as valuable spawning, rearing, and overwintering areas for riverine fish. Suitable slackwater habitat for migratory waterfowl, especially diving ducks, is also in short supply. On Stag Island itself, sediment "plugs" have formed in the opening of two sloughs, preventing optimal moist soil plant production in these areas in conjunction with Pool 25 water level manipulations for habitat improvement. The objectives of this project are to decrease sedimentation in the side channel between Stag Island and the Missouri shore, create high-quality winter habitat for fish, accumulate and maintain aquatic habitat structure (e.g., fallen trees, submerged logs, brush, etc.), create slackwater habitat for migratory waterfowl, and improve the slough habitats on Stag Island. After considering a full range of alternatives, the preferred plan was developed. To correct the local problem of sedimentation at Stag Island, and to enhance the surrounding habitat in general, a simple, cost-effective, single-component project was designed. The project involves the construction of a 1,300 foot long emergent stone dike extending from the Missouri shoreline to the tip of Stag Island. This dike will cross the upper end of the side channel and upper chute. It will have a crown elevation of 438 feet NGVD, or four feet above normal pool (434 feet NGVD). Revetments and rock armoring will be required at the head of Stag Island and at the Missouri bankline, and at the head of the unnamed island between the shoreline and Stag Island. The project will create about 127 acres of slackwater habitat from the 99-acre side channel and 28-acre upper chute. It is expected that sedimentation and turbidity will be reduced by the dike, water clarity will improve, submergent aquatic vegetation will become established, and woody debris will accumulate in the protected area. This slackwater area is expected to serve as spawning, rearing, and overwintering habitat for many riverine fishes, and as resting and feeding habitat for migratory birds, especially diving ducks. The dike is expected to retard the accumulation of sediments in sloughs on Stag Island, and delay the encroachment of woody vegetation in these productive units. Overall, aquatic habitat enhancement from the project would be anticipated to yield a net gain of 101 Average Annual Habitat Units (AAHUs). The project is designed to provide habitat benefits for approximately 50 years. A Project Performance Evaluation Plan (including physical and chemical analyses) that complies with the scope and methodologies used for other HREPs, and the Upper Mississippi River System-Long Term Resource Monitoring Program {UMPS-LTRM), has been developed. Pre-construction and post-construction monitoring would be implemented at a total annual cost of $7,050 but execution would be contingent upon EMP program reauthorization beyond the year 2002. MDOC, through a separate agreement with the USFWS, is the local sponsor for the Stag Island project. The USFWS Regional Director, and the St. Louis District Commander, will sign a Memorandum of Agreement (MOA) for restoring fish habitat resources at Stag Island, addressing the specific relationships, arrangements, and general procedures under which the USFWS and Department of the Army will participate in constructing, operating, maintaining, repairing and rehabilitating the project.
Description:	Definite Project Report with Integrated Environmental Assessment
Rights:	Approved for Public Release; Distribution is Unlimited
URI:	https://hdl.handle.net/11681/36695
Size:	124 pages / 18.74 MB
Types of Materials:	PDF/A
Appears in Collections:	Environmental Documents